Small steps on the slippery road to life: Molecular synthesis in astrophysical ices initiated by low energy electron impact

We report the synthesis and desorption of new chemical species from simple molecular surface ices irradiated by low energy (<60eV) electrons. For CD4 ices we observe the formation and desorption of energetic ions such as D-3(+), CD5+, and C2Dn+ (n = 2-5), as well as three carbon containing chains, that are also observed to desorb from C2D2 films; for oxygen rich methane ices we observe the synthesis and desorption of H2O+, H3O+, as well as formaldehyde type cations, viz., HnCO+ (n = 1-3), among others. The formation of all these pre-biotic molecular species, produced here by low-energy electron-impact-initiated cation-reactions in simple molecular films, suggests that similar mechanisms may lead to the synthesis of life's most basic molecular components in planetary, or astrophysical surface ices that are continuously subjected to the types of space radiations (UV, X- or gamma-ray, or heavy ions) that can generate such low energy secondary electrons. (C) 2008 Elsevier B.V. All rights reserved.